This invention relates generally to geomembranes of the type utilized in the fabrication of liners for earthen constructions such as landfills, canals, ponds, etc., and more particularly to an improved geomembrane comprising a unitary structure fabricated by co-extrusion.
Ground water contamination is a primary environmental concern. One method of controlling ground water contamination comprises the lining of landfills, canals, ponds, and similar earthen constructions with a liner comprising a geosynthetic clay liner and an underlying geomembrane. In this manner seepage from the lined construction into the underlying ground water is prevented.
More particularly, liners for landfills, canals, ponds, and similar earthen constructions may comprise a layer of bentonite. The upper surface of the bentonite layer is secured by a layer of woven polypropylene. A layer of non-woven polypropylene textile is positioned below the bentonite layer. A geomembrane is secured to the lower surface of the non-woven polypropylene textile which may be provided with a textured lower surface to prevent shifting of the liner relative to the underlying construction.
Heretofore the fabrication of liners in which a geomembrane is secured beneath a geosynthetic clay liner has been complicated by the necessity of applying a glue layer to the upper surface of the geomembrane in order to secure the geomembrane to the geosynthetic clay liner. The application of the glue layer has required a separate manufacturing step which has typically been carried out at a remote location. The cost of manufacturing the liner is therefore substantially increased.
The present invention comprises an improved geomembrane and method of manufacture which overcomes the foregoing and other difficulties which have long since characterized the prior art. More particularly, the present invention comprises an improved geomembrane construction which is directly bondable to a geosynthetic clay liner to complete the construction of a liner for landfills, canals, ponds, and similar constructions. In accordance with the preferred embodiment of the invention, the geomembrane comprises a unitary structure including an adhesive layer and a barrier layer which are fabricated by co-extrusion. The geomembrane of the present invention may further include a third co-extruded layer which may be textured.
By means of the present invention, the fabrication of liners for earthen constructions such as landfills, canals, ponds, and the like is greatly simplified. The improved geomembrane of the present invention is directly bondable to a geosynthetic clay liner to complete the construction of the liner, thereby eliminating the necessity of a separate adhesive application step. The use of the invention also results in an improved liner construction wherein the possibility of separation of the geomembrane from the remaining components of the liner is substantially eliminated.